The present invention relates to an improved method and apparatus for securing a lid to an opening of a container and particularly to containers of the type normally used to contain food products. Such containers are generally made of aluminum or similar metal, or plastic. In some instances, the containers have a substantially flat bottom with upwardly extending sidewall means that terminate to define the open end of the container and are further provided with a base flange extending outwardly from around the opening to the container to receive a lid closure and are further provided with a lip extending upwardly from the flange at the outer edges thereof so that a flat lid can be placed at rest on the base flange and lip turned inwardly to secure the lid.
While other closure arrangements can be provided where a lid is simply glued to an outwardly extending flange, arrangements of the type previously described are particularly useful, and almost necessary in packing food products to prevent unacceptable contamination of the product. Furthermore, equipment to seal packages by folding over an upstanding lip is generally more reliable and less expensive than corresponding equipment adapted to glue a lid in place.
In such arrangements where a lid is placed on the opening of a container, the container travels along a conveyor line where it is first filled with the material to be packaged. The lid is then placed on the container, for example, by devices in accordance with our co-pending application serial No. filed .
The container continues to travel along the conveyor to a station where the lid is secured in place by folding the lips over the lid and the finished package is then ready for shipment, or in some cases freezing.
One previous arrangement for securing lids on such containers is shown in U.S. Pat. No. 3,263,393, Weber, where an arrangement utilizing multiple rollers at various angles of vertical and horizontal inclination are utilized to fold the lip over the lid and secure the lid. While such arrangements are generally satisfactory in application, the equipment is cumbersome and expensive. Furthermore, it is necessary to carefully maintain the alignment of the rollers used in such arrangements. Since such arrangements are particularly susceptable to wear, and misalignment is a frequent problem, maintenance costs associated with such devices are significant.